SOLAR ECLIPSE

Caution
Protect your eyes! Don't look at the sun directly during a partial solar eclipse!

BLINDNESS will result from looking at the sun, either directly or through a viewfinder. Never look at the sun without adequate protection. Protecting your eyes adequately will reduce exposure to ultraviolet and infrared radiation, which can severely burn your eyes instantaneously without your immediately being aware of it. Also, adequate protection will increase eye comfort by reducing the intensity of the visible sun rays. NO FILTER IS USED DURING THE TOTAL ECLIPSE.

Viewing filter for partial phases

Always use a filter that will absorb sufficiently the ultraviolet, visible, and infrared energy of the sun. Special solar filters for viewing or photography are available.

If you are observing a total eclipse, during the few minutes of totality you do not need a viewing filter. However, as soon as totality ends, begin using the viewing filter again.

Do not use color film, KODAK WRATTEN Neutral Density Filters, or crossed polarizing material as a viewing filter. These items will not protect your eyes as they do not absorb the ultraviolet and infrared rays sufficiently.

Focal Length of Lens

The high light intensity of the sun even during an eclipse permits you to use any camera. However, the size of the sun or moon image depends on the focal length of the camera lens. You can estimate the actual image size on the film by dividing the focal length by 110. For example, with a camera lens having a focal length of 4 inches (100 mm), the image size would be about 4/110 inch (1 mm) in diameter--the thickness of a dime. However, many good pictures of eclipses have been made with 35 mm cameras equipped with lenses of 2-inch (50 mm) focal length. So don't put your camera away because you don't have a long-focal-length lens.

In movies of the eclipse, the image will be enlarged when projected on the screen. Assuming a magnification of 110 diameters on projection, the diameter of the image of the sun on the screen will be approximately equal to the focal length of your camera lens.

Camera Protection

The sun can burn holes in focal-plane shutters, warp the leaves of between-the-lens shutters, and melt composition shutter blades. Use neutral density filters that are made for photographic use. These will help you take properly exposed photos but will not protect your equipment. If your camera must be pointed toward the sun throughout the eclipse, shade it between exposures. It is wise to shade the camera from direct sunlight at all times to avoid overheating film and camera.

Aiming Your Camera

NEVER LOOK AT THE SUN THROUGH A CAMERA VIEWFINDER WITHOUT SUITABLE FILTERS EVEN FOR A BRIEF TIME. This is especially important with single-lens reflex cameras. The best policy is to aim your camera without using its viewfinder. If you must use the viewfinder, use solar filters, as noted before, held in front of the viewfinder or, with a single-lens reflex camera, in front of the camera lens.

FILTERS MADE FOR PHOTOGRAPHIC USE GIVE NO VISUAL PROTECTION. Therefore, use the solar filters for visual aiming and photography. If you don't have a solar filter, aim without using the viewfinder and change to neutral density filters made for photographic use to take pictures of the eclipse (see below) Once you have changed to neutral density filters for use on your camera, do not look through the viewfinder.

Exposure

The light from the sun's surface is so intense that in order to photograph the partial phases of the eclipse, you must reduce the sun's light by 10,000 to 100,000 times. Neutral density filters (ND) provide the most convenient way of cutting down the light to allow normal camera exposures. During the partial phases, the light intensity of the surface of the sun is the same as it is when there is no eclipse.

Here is a simple formula for determining the correct exposure for the partial phases:
f ² = S x t x 10²-D

For example, with a neutral density filter of 5.0, KODACHROME 64 Film, and a shutter speed of 1/125 second, you would use a lens opening of f/8; with a shutter speed of 1/30 second, you would use a lens opening of f/16.

Additional exposure information is given in the table "Solar Eclipse--Approximate Exposures for Still Cameras". If you are taking pictures with a simple nonadjustable camera, use KODAK PROFESSIONAL T-MAX 100 Film and a 5.0 ND (neutral density) filter during the partial phases. Remove the ND filter only during totality.

The brightness of the sun does not change during the eclipse (except when it is total), so your exposure during partial phases should remain constant as long as sky conditions remain constant. Most camera exposure meters average the reading over some area. If the visible portion of the sun does not cover all this area, the meter will indicate more exposure than needed.

If you have a camera with automatic exposure control, consult your camera manual to override the automatic exposure system; or see your local camera dealer.

What to Photograph During a Solar Eclipse

Partial phases. Beginning about 1 hour before totality, you can see the moon gradually encroaching on the sun's disk; for about 1 hour after totality, the shadow gradually retreats. You can obtain an interesting record of the eclipse by mounting your camera onto a firm support and making a series of exposures at 5-minute intervals on the same frame of film, starting a half hour before totality and continuing for a half hour after. For this technique, you'll need to use a camera which will let you take more than one exposure on the same frame of film. Check your camera manual to see if you can do this with your camera.

The period over which you can make such a record on a single frame depends on the angle of view of your camera lens. The position of the sun will change about 15 degrees per hour. A normal-focal-length camera lens will cover a sufficient angle for exposures over a 2-hour period. Watch your local newspaper for the timing of the progress of the moon across the sun disk; then plan your camera position and exposure schedule accordingly. Better yet, practice the day before.

Shadows under trees. All during the partial phases, the sunlight filtering through the leaves of trees forms images of the eclipsed sun on the ground. You can photograph these crescents easily with normal exposures for the film you're using.

Shadow bands. During the last few seconds before totality, you may see wave-like shadows called shadow bands moving over the ground. They average from 1 to 2 inches in width and are 5 or 6 inches apart. They are most easily visible on a white background, such as a bed sheet.

This phenomenon is very difficult to photograph because of the low illumination and the speed of movement. With a white sheet on the ground to obtain as high reflectance as possible, you can expose T-MAX 400 Film at 1/125 second with a lens opening of f/2. If the largest lens opening on your camera is f/3.5, to record the shadow bands you can use KODAK PROFESSIONAL T-MAX P3200 Film for a camera that accepts 135-size film or T-MAX 400 Film (pushed 1 or 2 stops) for a camera that accepts 120-size film.

Landscape during totality. The intensity of the available illumination varies rapidly during the minute just before, and the minute just after, totality. At the darkest period (during totality), an exposure of about l/4 second at f/8 on KODAK PROFESSIONAL EKTACHROME Film E200 should give good results for landscape photography.

During totality, you may not be able to see the settings on your camera. Carry a pocket flashlight so that you can check or change your camera settings.

Total eclipse. Totality usually lasts less than 5 minutes. Therefore, it is a good idea to go through a few practice runs and time yourself so that you can take several pictures during this brief period.

Baily's beads. For an instant just before totality and again just as the sun emerges, light breaks through the valleys on the rim of the moon, forming what looks like a beaded necklace along the edge of the moon. This brief display is very spectacular.

Use a shutter speed of 1/500 second, no filter, and the same lens opening recommended for partial phases in the table "Solar Eclipse--Approximate Exposures for Still Cameras".

The diamond-ring effect can be photographed by adjusting exposure for the prominences without the neutral-density filter.

Caution
Do NOT remove the filter too soon! If you do, severe eye damage can result.

Corona. At totality, the corona appears around the sun as a beautiful halo, decreasing in brightness from the moon's rim outward. Points of interest to observe and photograph in the outer corona are the equatorial streamers, which may extend several diameters from the sun. Superimposed on the inner corona are solar prominences, scarlet, tongue-like jets shooting outward from the sun surface.

Since the intensity of the corona fades rapidly away from the solar limb (edge of the sun's apparent disk), the distance to which the photograph will show the corona depends on the exposure--the longer the exposure, the greater the extension. However, if you attempt to record the faint outer streamers, then the inner corona will be overexposed. The most colorful results are often obtained with a shorter exposure gauged to record the inner corona. As an aid in capturing both effects on the same piece of film, use color negative film and selective printing.

Telescope or Binocular

You can use a small telescope or binocular in conjunction with an ordinary camera. The image size obtained with such a combination will be equal to that obtained with your camera alone multiplied by the power of the telescope or binocular. It is best to build some type of rigid support to hold your telescope and camera in alignment.

You can arrive at the best focus and exposure for the partial phases experimentally by photographing the sun prior to the eclipse. Make an approximate focus setting by focusing the telescope or binocular on an object at a great distance. Then set your camera lens at infinity, and focus at the largest lens opening. Join the camera and telescope, covering the space between the camera lens and the eyepiece of the telescope with a black cloth to cut out stray light. See section entitled "Telescope".

Camera Support

For a series of pictures of the partial phases, mount your camera on a tripod or other rigid support to prevent movement between exposures. Also, with long-focal-length lenses, a telescope or a binocular, a solid support is essential to avoid loss of definition due to camera motion.

Because of the Earth's rotation, solar images 1 inch in diameter or greater will show significant movement on the film during exposures of 1/6 second or more. For these and longer exposures, use an equatorial mounting with a clock drive. If your exposures exceed 1 second and no drive mechanism is available, the diameter of the solar image should be proportionately smaller as exposure times are increased.

Filters

Caution
Filters made for photographic use give NO VISUAL PROTECTION. Do not try to observe a solar eclipse through such filters because they transmit infrared energy which can burn your eyes.

The use of neutral density filters is a convenient way of reducing the excessive light intensity for photography during the partial phases. You can quickly remove the filters from in front of the lens at totality.

The KODAK WRATTEN Neutral Density Filter No. 96 (gelatin) is available in the following densities: 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 2.00, 3.00, and 4.00. You can obtain intermediate densities or higher densities, such as 5.0 and 6.0, by combining two of the standard filters. However, if you use more than two at one time, image sharpness will be reduced. These filters are available through photo dealers.

Neutral density filters

When you use neutral density filters, be sure you don't confuse their density values. For example, a 0.50 neutral density filter reduces the light by approximately 3 times while a 5.0 neutral density filter reduces the light by 100,000 times.

Some neutral density filters are identified as 2X, 4X, 8X, and 10X. These designations indicate the filter factor and are equivalent to the following densities: 2X = 0.30, 4X = 0.60, 8X = 0.90, and 10X = 1.00. The filter factor indicates how many times the filter reduces the light. For example, a filter factor of 4 means that the filter reduces the light by 4 times.

Be sure of terminology when ordering neutral density filters. Obtain a 4.0 filter, not a 0.40 or 4X filter.

Although gelatin-film neutral density filters are protected by a thin lacquer coating, you should handle these filters only by the edges or at the extreme corners. The KODAK Gelatin Filter Frame, a two-part metal frame, is a convenient accessory for handling gelatin filters. You can use the filter frame with the KODAK Gelatin Filter Frame Holder, which you attach to your camera lens with an appropriate adapter ring. The filter frame holder is convenient to use because you can change filters rapidly, but it's not a necessity. You can attach the filter frame, or even the filters alone, to the lens with small strips of pressure-sensitive tape.

Exposure Table

The exposure recommendations in the table entitled table "Solar Eclipse--Approximate Exposures for Still Cameras" are based on results obtained in actual solar eclipse photography with clear viewing conditions. So much depends on atmospheric conditions, however, that you should regard these exposures only as approximate guides.

Exposure for each phase of the eclipse, especially during totality, can vary over a wide range and still produce good photographs. If you take several pictures at different exposure times and settings, each picture should show different details of the eclipse. Therefore, for the best coverage, bracket the suggested exposure. Take pictures at the estimated exposure and at 1, 2, and 3 stops less exposure and more exposure than the estimate.

You can calculate exposure times for lens openings other than those given in the table. Suppose the effective lens opening of your lens is f/32 and the table suggests f/8. Divide 32 by 8 and square the answer

Therefore a lens opening of f/32 will require an exposure 16 times as long as that required at f/8.

Solar Eclipse--Approximate Exposures for Still Cameras

ISO Speed	Partial Phases	Totality (prominences)	Totality (inner corona)	Totality (outer corona)
25--32	f/5.6 5.0 ND 1/125	f/3.5 No Filter 1/125	f/3.5 No Filter 1/15	f/3.5 No Filter 1/2
40--50	f/6.3 5.0 ND 1/125	f/4.5 No Filter 1/125	f/4.5 No Filter 1/15	f/4.5 No Filter 1/2
64--100	f/8 5.0 ND 1/125	f/5.6 No Filter 1/125	f/5.6 No Filter 1/15	f/5.6 No Filter 1/2
125--160	f/11 5.0 ND 1/125	f/8 No Filter 1/125	f/8 No Filter 1/15	f/8 No Filter 1/2
200--250	f/16 5.0 ND 1/125	f/11 No Filter 1/125	f/11 No Filter 1/15	f/11 No Filter 1/2
400--650	f/16 5.0 ND 1/250	f/16 No Filter 1/125	f/16 No Filter 1/15	f/16 No Filter 1/2
1000--1250	f/16 5.0 ND 1/500	f/16 No Filter 1/250	f/16 No Filter 1/30	f/16 No Filter 1/4

Note: ND indicates neutral density filter. Equivalent exposures may be used: 5.0 ND at f/11, 3.0 + 2.0 ND at f/11, or 4.0 ND at f/32 approximately.

KODAK Films

For the partial phases, you can use any film for general photography. For the most interesting phases of an eclipse, those occurring during totality, a high-speed film is desirable. The following films are suggested for photographing the eclipse. You can use the ISO speeds with the "Solar Eclipse--Approximate Exposures for Still Cameras" and with the formula referenced in "Exposure".

Contents | Getting Started | Solar Eclipse | Lunar Eclipse

P-150  • April, 2002